Sometimes, the timer visual effect of spell alerts shrinks very quickly, around 5 secs (independently of the actual timer remaining). Sometimes it quickly shrinks after leaving combat, within approximately 1 second. Both can happen at the same time. In either case, the spell alert does not end when the timer ends. Instead, the alert lingers with half opacity (that is, opacity of depleted time) until the buff actually expires, at which time the alert is removed as intended.

Sometimes, re-entering combat before the buff expires will not restore its full opacity. With coordinated textures e.g. "Left + Right (Flipped)", re-entering combat may re-opacify only one of the textures.

This issue has been first observed with Mage's Clearcasting on Cataclysm Beta, where it is almost always problematic. Since then, it has been observed on other spell alerts, such as Death Knight's Killing Machine, although the issue is not consistent. Usually it works as intended for the first proc, and never works afterwards.

When activating Debug and Trace information, the remaining time is correctly detected. For example, Killing Machine has a 30-second duration. Logs indicate that the addon sets the timer to 30 seconds and nothing else.

Based on symptoms and recent development timeline, it may have been introduced during #211, although it has yet to be formally proven.

Confirmed it was introduced in 23a450f. Unfortunately, simply reverting this commit introduces other side effects. #289 will fix it, but re-introduces #288.